IVcsControl: Add additionalToolsPath()

Add a method for a VCS to tell creator where it installed additional
tools that it came with. This is useful for e.g. git on windows
which ships with a nice bunch of unix tools.

Change-Id: Ibc5f2fb57307bfadad140bd57d83917e56d57153
Reviewed-by: Orgad Shaneh <orgads@gmail.com>
VcsBaseClientSettings: Add method to retrieve VCS client search path

Change-Id: I7aff223cdbc108fc51554a5f53f8c5efb3856864
Reviewed-by: Orgad Shaneh <orgads@gmail.com>
Git: Report additional search paths

Change-Id: I07d9ea0946ec44b4d1a7d7d02b1f50dbaf78f6e6
Reviewed-by: Orgad Shaneh <orgads@gmail.com>